Control system

ABSTRACT

A control system for a motion picture projection installation having a pair of lengths of motion picture film passed along separate film paths through separate reversible drive means between a pair of reels upon which the films are cowound in reciprocal head-to-tail bifilar relation. The control system includes means for sensing the quantity of film present in one of the film paths between one reel and film display means located intermediate the reels. The control system also includes means for controlling the drive means to maintain said film quantity between predetermined limits.

United States Patent Taillon [54] CONTROL SYSTEM If l a 1 I -l I [451Sept. 12,1972

3,318,544 5/1967 Jones, Jr ..242/ 190 Primary ExaminerS. Clement SwisherAttorney-Christie, Parker & l-lale [57] ABSTRACT A control system for amotion picture projection installation having a pair of lengths ofmotion picture film passed along separate film paths through separatereversible drive means between a pair of reels upon which the films arecowound in reciprocal head-to-tail bifilar relation. The control systemincludes means for sensing the quantity of film present in one of thefilm paths between one reel and film display means located intermediatethe reels. The control system also includes means for controlling thedrive means to maintain said film quantity between predetermined limits.

5 Claims, 16 Drawing Figures PATENTEDSEP 12 1912 3.690.750

sum 02 or 15 DNQQK w .QQQR NQSQ m k PATENTED 12 I973 3.690.750

SHEEI UHUF 15 PATENTEDsEP 12 I972 3.6 90.750

sum 07 or 15 PATENTEDSEP 12 m2 SHEET llfiF 15 PATENTEDSEP 12 I972 SHEET120F 15 Q TAWNN MNK PATENTED SEP 12 I972 SHEEI 1% 0F 15 1 CONTROL SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS This is a division of mycopending application 'Ser. No. 795,992, filed Feb. 3, 1969 now US Pat.No. 3,552,842.

FIELD OF TI-IEINVENTION head-to-tail bifilar relation .on a pair ofreels defining the ends of two separate filmpaths.

BACKGROUND OF THE INVENTION US Pat. No. 3,379,488 describesa'motionpicture display system which has utility in the passengercompartment of commercial aircraft, as well as in classrooms and thelike.

So that a motion picture projection system may have enhanced utility insuch areas, it is desirable that the projection system be arranged foroperation by relatively unskilled personnel such as airline stewardessesor teachers, ratherthan trained projectionists. Ideally, especiallywhere the projection system is to be used to display a motion pictureprogram of specified content a number of times, it is desirable that theneed for rewinding film be minimized, if notaltogether eliminated. Theelimination of film rewinding is of particular economic significancewhere a projection system is used in the-passenger aircraft-ofinternational air carriers; the servicing of such systems forthe-purposes .of film rereeling involves the use of trained "personnelwhich are not normally maintained'on thesta'ff of the .carrier and whichare obtainable in many countries only atpremium wages, if at all.

To overcome the problems which, .to .date, have worked to the economicdisadvantage of motion picture projection systems aboard the aircraft ofinternational airlines, an improvedmotion picture projection system hasbeen proposed. The improved projection system includes a pair offilmstorage reels and a pairof lengths of motion picture ifilm .cowoundin reciprocal head-to-tail bifilar'relation upon the reels. The films.are passed along separate paths between thereels through projectionmeans located intermediate the reels. Separate film advance mechanisms,each having a reversible drive motor, are associated with the filmsbetween the reels for drivingthe filmlengths between the reels. The filmlengths define respective halves of a motion picture program ofspecified content; that is, eachfilm may define a separatefeature-length motion picture, orthe two film lengths'may definerespective halves of a singlefeature-lengthrmotion picture. Duringoperation of the'system, the information carried by that film whichmoves in a forward mode between the reels is displayed, the informationcarried by the other film length being displayed when the films move inthe opposite direction between the reels.

It is inherent in this projection system that the films arch the samestate upon completion of display of'the entire program as they wereatthe time display of the program was commenced. This feature issignificant because the system may be operated repeatedly to display thesame 'program without rereeling the film between program presentations;of course, it is necessary to remove the film from the system if thecontent of the-program is to be changed. Such a motion pictureprojection system is readily usable in the passenger compartments ofaircraft operated by international air carriers, as well as inclassrooms, small theatres, and in myriad other situations. In any ofthese usages, however, it is desirable that the projection system beessentially self-regulating so that the person responsible for operationof the system need'not do much more than merely turnthe system ON tocommence program display and turn the system OFF when the programdisplayed is completed.

Thepresently preferred use of this projection system is in the passengercompartments of commercial passenger aircraft.

SUMMARY OF THE INVENTION This invention provides a control system forthe improved motion picture projection system described above. Thecontrol system provides automatic control over the rate at which film istaken from and supplied to the reels, and also automatically regulatesthe amount of film which is present in the respective film paths. Thecontrol system is arranged to minimize the attention which an operatormust give'to the projection system during its operation. The controlsystem is arranged so that the equipment required to achieve the desiredcontrol functions is minimized, and so that the nature of the film'pathsbetween the two reels may be as simple as possible. The simplificationof the film paths extends the useful life of the film itself, andincreases .the number of times the system may be operated to display thesame program before the film must be removed from the projection systemfor cleaning and conditioning. These desirable features of the controlsystem flow from the fact that, due to .the cowound 'bifilar relation ofthe films on the reels, the basic behavior of one film is reflected inthe basic behavior of the other film. That is, in general terms, eachfilm is slaved to the other during movement of the films between thereels, and the necessary control functions provided by the controlsystem are divided between the films so that film tension sensingoperations required to generate the desired control signals aredistributed substantially equally between the films. The system also hasthe feature that, upon completion of one mode of operation thereof, thesystem resets itself to provide appropriate control during subsequentoperation of the system in the other mode; that is, the control systemhas a memory and remembers how it operated duringthe prior operation ofthe associated projection system.

Generally speaking,.this invention provides a control apparatus fora'motion picture projection system which includes a pair of film storagereels. A pair of film lengths are cowound on the reels in reciprocalhead-totail bifilar relation, and are passed between the -reels alongseparate film paths. Display means are located along the film pathsbetween the reels. The projection system alsoincludes reversible drivemeans associated with each film length-along its path for driving thefilm between the ."reels. The ;control apparatus includes means forsensing a change in the quantity of film present in one of the filmpaths between one of the reels and the display means. The controlapparatus also includes means responsive to the sensing means forcontrolling operation of the drive means when the sensing means discernsa change in film quantity in excess of a predetermined amount.

Preferably, the rate at which film is unreeled from and reeled upon therespective reels is controlled by information derived f'rom one of thefilm lengths, and the rate at which the drive means are operated to movefilm between the reels is controlled from information derived from theother film path.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features ofthis invention are more fully set forth in the following detaileddescription of a presently preferred embodiment of the control system,which description is presented with reference to the accompanyingdrawings, wherein:

FIG. 1 is a simplified schematic representation of the control systemand its relation to a motion picture projection system of the typedescribed above;

FIG. 2 is an elevation view of an operators central control panel;

FIG. 3 illustrates the relationship of the schematic diagrams of FIGS.3A through 3K;

FIGS. 3A through 3K are schematic diagrams of separate portions of thecontrol system, such diagrams being related to each other in the mannerillustrated in FIG. 3;

FIG. 4 is a fragmentary elevation view of a portion of the mechanismprovided adjacent each film storage reel for regulating the rotationalrate of the reel; and

FIG. 5 is a cross-sectional elevation view of a portion of the structureshown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, thepresently preferred use of a control system according to this inventionis in combination with a motion picture projection system 12 whichincludes a pair of projection stations 13 and 14 and a pair of reelstations 15 and 16. In the following description, projection station 13is sometimes referred to as the No. 1 projection station, projectionstation 14 is sometimes referred to as the No. 2 projection station,reel station 15 is sometimes referred to as the No. 1 reel station, andreel station 16 is sometimes referred to as the No. 2 reel station.

Reel stations 15 and 16 include, respectively, reels l7 and 18 uponwhich are cowound, in reciprocal head-to-tail bifilar relation, a pairof film lengths 19 and film length 19 is sometimes referred tohereinafter as the No. l film and film length 20 is sometimes referredto as the No. 2 film. Film lengths l9 and 20 define the first and secondhalves, respectively, of a motion picture program of specified content.A program of specified content may include two featurel'ength motionpictures, in which case reels l7 and 18 are of sufficient capacity tostore both films essentially fully thereon. The term program ofspecified content" also encompasses a single feature-length motionpicture, in which case film length 19 defines the fist half of thepicture and film length 20 defines the second half of the picture. Filmlengths 19 and 20 are of essentially equal length and are actually twoseparate lengths of film.

The reciprocal head-to-tail bifilar relation of film lengths l9 and 20on reels l7 and 18 may be understood best by assuming that the motionpicture program is constituted of a single feature-length motionpicture. Assume further that the single film length is folded uponitself at its midlength so that the head end of the portion of the filmdefining the first half of the program is placed in overlying relationto the tail end of the portion of the film defining the second half ofthe program, and so that the tail end of the portion of the filmdefining the first half of the program is placed in overlying relationto the head end of the second half of the program. In this head-to-tailrelationship, the film is wound upon reel 17 so that the tail end of thefirst half of the program and the head end of the second half of theprogram (i.e., the location where the film is folded on itself) areconnected to the core of reel 17, and the head end of the first half ofthe program and the tail end of the second half of the program areconnected to the core of reel 18. Between the reels, the separate halvesof the film are threaded along separate film paths through projectionstations 13 and 14, respectively. Because the halves of the folded filmare wound in overlying relationship on reels l7 and 18, the film isproperly said to be cowound in reciprocal head-to-tail bifilar relationupon the reels.

Projection system 12 has two modes in operation. In its A mode, theprojection system is operated to move film from reel 17 to reel 18. Inits B mode, the projection system is operated to transfer film from reel18 to reel 17. When the projection system is threaded with filmaccording to the procedure described above and is operated in its Amode, the frames of film length 19 move in a forward sequence or modethrough projection station 13, and the frames of film length 20 move ina reverse sequence or mode through projection station 14. Conversely,when the system is operated in its B mode, film length 19 moves in areverse mode past optical axis 21 of projection station 13, and filmlength 20 moves in a forward" mode past optical axis 22 of projectionstation 14.

Each of projection stations 13 and 14 defines what is substantially aconventional motion picture projection. Thus, projector station 13includes a lens assembly 25 aligned along optical axis 21 between a pairof film drive sprockets 26; the sprockets constitute a part of anessentially conventional film advance mechanism driven by a reversiblemotor 27. Located in line with optical axis 21, and on the opposite sideof film length 19 from the projection lens assembly, is a projectionlamp 28 which is located next to a spare projection lamp 29; thecounterparts in projection station 14 of the components of station 13are identified by corresponding primed numbers, this expedient beingutilized for simplification of the illustration of FIG. 1. A fireshutter 30 is disposed in projection station 13 between lamp 28 and thepath of film 19, and is operated by a solenoid 31. Projection station 13also includes a forward-mode shuttle-loop restoring mechanism 32;mechanism 32 is of conventional design and preferably is of the typeencountered in commercially available motion picture projectorsmanufactured by Bell & Howell Company. Projection station 13 alsoincludes a reverse-mode shuttle-loop restoring mechanism 33 which is ofdifferent design from mechanism 32 and constitutes a novel feature ofthe present invention.

Projection station 13 further includes an audio pickup device 34 whichcooperates with film length 19 downstream of optical axis 20 during Amode operation of projection system 12. That is, audio pickup device 34is located between optical axis 21 and reel 18 along the path of filmlength 19. Projection station 14 includes an audio pickup device 34'which is disposed between optical axis 22 and reel 17 along the path offilm length 20. Audio pickup devices 34 and 34' may be of the opticaltype or of the magnetic type, as desired. In a presently preferred formof projection system 12, projection stations 13 and 14 are identical,and are arranged in erect side-by-side relation with optical axes 21 and22 thereof directed to a common display screen. The positional reversalof audio pickup devices 34 and 34 relative to their respective filmlengths is obtained by the manner in which the film lengths are threadedthrough the projection system. This threading arrangement is not a partof the present invention and, therefore, is not described herein.

It will be observed from an examination of FIG. 1 that the locations ofthe forward-mode and the reversemode shuttle-loop restoring mechanismsof projector 13 are reversed relative to the corresponding com ponentsof projector 14, but occupy the same relative positions along theadjacent film paths when the respective films are moved in a forwardmode through the projectors.

Projection lamps 28 and 29 of projection station 13, are mounted inside-by-side relation upon a springloaded, slidable shuttle plate (notshown) which normally is positioned so that lamp 28 is aligned withoptical axis 21, and similarly with projection lamps 28' and 29' ofprojection station 14. The shuttle plates are moved by the spring biasapplied thereto upon operation of a corresponding spare lamp solenoidK12 and K16 (not shown in FIG. 1, but see FIG. 3) to move to their otherlimit of travel in which spare lamps 29 and 29, respectively, arealigned with the respective optical axes. Upon arrival of theappropriate shuttle plate at the limit which places the spare lamp inalignment with the respective optical axis, a limit switch S24 or S (notshown in FIG. 1, but see FIG. 3) is operated. The details of the sparelamp arrangement, the shuttle plates, and drive mechanisms therefor, areshown in commonly-owned copending application Ser. No. 639,462, filedMay 18, 1967.

Fire shutters 30 and 30' are provided to protect film lengths 19 and 20,respectively, from exposure to heat from the projection lamps when thefilm lengths are stationary relative to the corresponding optical axes,thereby to prevent burning of the film. The fire shutters are alsointerposed between the projection lamps and the films during theinterval following start-up of the projection system in either of itsoperational modes, within which interval the projection lamps heat upand assume their full operational brightness.

Each of film storage reels 17 and 18 is coupled to a reel drive motor or36, respectively, via a variably effective coupling mechanism 37, 38,respectively. With reference to reel station 15, coupling mechanism 37is controlled by the tension in film length 20 adjacent reel 17. Closelyadjacent the periphery of reel 17, film length 20 passes around rollers39, 40 and 41, each of which has a prime numbered counterpart in reelstation 16. Rollers 39 and 41 are mounted for rotation about fixed axes,but roller 40 is mounted to a sensing lever 42 having a fulcrum 43.Lever 42 is connected to a biasing spring 44, and is connected by apivoting linkage assembly 45 to a structure 46 of mechanism 37 which isengaged more directly between reel drive motor 35 and reel 17. Elements39 through 46 are all components of coupling mechanism 37 and,similarly, at reel station 16, elements 39 and 46 are components ofcoupling mechanism 38. The coupling mechanisms are essentially identicaland are effective to increase or decrease the driving connection of thereel drive motors with the respective reels depending upon (1) thetension of the film engaged with the sensing rollers thereof, and (2)whether the appropriate reel station is functioning to pay out or toreel in film within projection system 12. The connection of the reeldrive motors with the corresponding film storage reels preferably is viaa belt, and in this regard, mechanisms 37 and 38 are substantially inaccord with the disclosures of US. Pat. No. 3,398,914 except to theextent illustrated in FIGS. 4 and 5 and described in greater detailhereinafter. Reel drive motors 35 and 36 preferably are reversiblesynchronous motors which are operated at constant speed. It should beobserved at this point that the angular velocity of reels 17 and 18 iscontrolled by information derived from the state of the No.2 film, i.e.,film length 20.

Reel station 15 includes a normally closed end-offilm switch 48 which isoperated by a sensing roller 49 which, during operation of projectionsystem 12, rides against film length 19 to maintain the switch contactsin an open state. Reel station 16 includes a corresponding end-of-filmswitch 48'. Sensing rollers 49 and 49' are disposed in-line with theposition occupied in film length 19 by control apertures 50 (see reelstation 16) which are disposed at selected locations along film length19. Preferably, apertures 50 are disposed adjacent the opposite ends ofthe film. As will be described below, the sensing of apertures 50 byeither of switches 48 or 48' causes the projection system to be shutdown, and also produces an adjustment in the state of the logicalcontrol mechanisms within control system 10; in this regard, it shouldbe noted that the presently preferred use of projection system 12 is inthe passenger compartment of a commercial aircraft in conjunction with afilm program constituted of two full length motion pictures.

Projection station 15 includes a looper assembly 52 which is comprisedof a plurality of rollers 53 mounted for rotation about stationary axesand a plurality of rollers 54 which are mounted to a common movablecarriage 55 biased relative to rollers 53 by a constant force springmechanism 56 to maintain essentially constant tension in film threadedthrough the looper in the manner illustrated schematically in FIG. 1.Roller carriage 55 cooperates with a slack sensing switch 57 and atension sensing switch 58 which are located in spaced relation to eachother along the path of movement of the carriage 55. Reel station 16 hasassociated with it a second looper assembly 60 which includes components61 through 66 which correspond in structure and function to components53 through 58, respectively, of looper assembly 52. Looper assembly 52functions to sense a change in the quantity of film present in the pathof film length 19 between reel 17 and projection station 13. Similarly,looper assembly 60 functions to sense a change in the quantity of filmpresent in the path of film 19 between reel 18 and projection station13. As will be described below, control system 10, to which switches 57,58, 65 and 66 are connected, operates to provide corrective actionwithin projection system 12 when the extent of change sensed by thelooper assemblies exceeds a predetermined amount.

The operational mode (forward or reverse) of motors 27, 27, 35 and 36 ofprojection system 12 is determined by control system 10. Similarly, theoperation of the forward-mode and reverse-mode shuttle-loop restoringmechanisms and of the fire shutter solenoids is regulated by the controlsystem in response to information supplied to the control system by theend-offilm sensing switches and by the film slack and film tensionsensing switches of the looper assemblies. The selection of which of theprojection lamps and the audio pickup devices is operative at any giventime is also determined by the operation of control system 10.

It will be observed from an examination of FIG. 1 that the signals whichcontrol the logical operation of the control system are all derived fromthe state of the No. 1 film, i.e., film length 19. As noted above, thesignals which determine the rate at which reels l7 and 18 are driven bytheir respective drive motors is derived entirely from the No. 2 film.This association of distinct control functions within system 12 withrespective ones of the two films present in the projection system ismade possible because the films are reciprocally slaved to each other byreason of their cowound bifilar relation upon reels 17 and 18. That is,film length 19 is payed out from reel 17, or reeled onto reel 17, at thesame rate as film length 20. Similarly, the presence of an excessquantity of film in the path of film length 19 between reel 17 andprojection station 13 will, except in exceptional circumstances, beassociated with a corresponding deficiency in the amount of film presentin the same film path between projection station 13 and reel 18; similarexcesses and deficiencies of film normally will occur in thecorresponding portions of the path of film length 20. That is, becausethe bifilar relation of film lengths l9 and 20 upon reels l7 and 18necessarily results in the film lengths being payed out from or takenonto the reels at equal rates at either reel station, but notnecessarily at both reel stations, the operation of variably effectivecoupling mechanisms 37 and 38 may be controlled from only one of thefilm lengths. Similarly, as will be made clear from the followingdetailed description of the operation of control system 10, informationderived from the looper assemblies may be used to advantage to controlthe movement of film length 20 through projection station 14. A changein the rate at which either film is moved through its projection stationwill have a corresponding effect in the state of looper mechanisms 52and 60.

FIG. 1 should not be interrupted to suggest that all informationgathering switches which have an effect upon control system 10 areassociated with the reel stations or with the projection stations. Asnoted above, the presently preferred use of projection system 12 is inthe passenger compartment of a commercial aircraft; actually, theaircraft includes three projection systems, each of which is in accordwith the illustrations of FIG. 1 and the foregoing description. Thesethree projection systems normally are controlled, at least as to filmselection, START and STOP commands, and spare lamp injection, from acentral control station defined by a stewardess control panel 69, anelevation view of which is provided in FIG. 2.

The face of the stewardess remote control panel is divided into threebasic areas 70, 71 and 72, corresponding to the forward, center and aftprojection systems installed within the aircraft. Each of panel areas70, 71 and 72 includes a plurality of illuminated push button switchesas follows: SHOW switch 73, CYCLE switch 74, START switch 75, MOVIE No.1 switch 76, MOVIE No. 2 switch 77, OFF switch 78, and SPARE LAMP switch79. The control panel 69 also includes an illuminated SEAT MUSIC pushbutton switch which is operable to supply stereophonic music to theheadphone connections associated with the various seats in the aircraft,via the motion picture projection systems, in a manner which isconventional and does not form a part of this invention. Panel 69 alsoincludes a key-operated POWER ON/OFF switch 81 which is operable by thestewardess to connect the aircraft 400 cycle three-phase power system tothe several control systems 10. A pair of holders 82 are mounted to theface of the control panel to receive legend cards bearing the names ofthe motion pictures defined by film lengths 19 and 20, respectively.Each of switches 73-78 is connected in parallel with a correspondingswitch or relay located within a control box 84 located within thehousing of the projection system to which the several switches arepertinent. Switch 81 is connected in series with a corresponding powerswitch S8 in each control system 10 within the aircraft.

Referring now to FIG. 3, and the several portions 3A-3K thereof whichcollectively set forth a schematic wiring diagram of control system 10,a plurality of leads 85105 connect remote control panel 69 with theseveral identical control boxes 84 within the aircraft. These leads aredesignated as follows:

LEAD DESIGNATION 85 Pilot keying ground" which, when energized, connectsa pilot intercom into the audio circuitry of the projection system;

"Movie No. 1 indicator" which, when energized, causes illumination ofpush button 76 for the projection system;

Movie No. 2 indicator" which, when energized, produces illumination ofpush button 77 for the projection system;

Spare lamp switch" which, when energized,

produces operation of the spare lamp shuttle mechanism associated withthat projection station operating in a forward mode in the projectionsystem; lead 88 is energized by operation of switch 79 at remote controlpanel 69;

Spare lamp indicator which is energized by operation of the limit switchassociated with the projection lamp shuttle plate associated with lead88;

"AC ground;

1. Apparatus for controlling a motion picture projection systemcomprising: a film supply reel; a film takeup reel; a length of filmstored on and extending along a predetermined film path between the filmreels; a motion picture film projector disposed along the film path andarranged so as to have the film pass in operative projecting relationtherethrough; first film control means located between the supply reeland the motion picture projector for dynamically storing a portion ofthe film and for sensing deviations in the film tension to provide acontrol reaction; and second film control means located between themotion picture projector and the takeup reel for dynamically storing aportion of the film and for sensing deviations in the film tension toprovide a control reaction.
 2. Apparatus according to claim 1 whereinsaid film control means includes first sensing means for detecting apredetermined increase in film tension; and second sensing means fordetecting a predetermined decrease in film tension.
 3. Apparatusaccording to claim 2 wherein said first and second control meansincludes a constant force spring mechanism for maintaining constanttension in the film.
 4. Apparatus for controlling a motion pictureprojection system comprising: a film supply reel; first film drive meansoperatively associated with the film supply reel for dispensing filmtherefrom during apparatus operation; a film takeup reel; second filmdrive means operatively associated with the film takeup reel forgathering film during apparatus operation; a length of film stored inand extending along a predetermined film path between the film supplyand takeup reels during apparatus operation; a single motion picturefilm projector disposed along the film path and arranged so as to havethe film pass in operative projecting relation therethrough; first filmcontrol means located between the film supply reel and the motionpicture projector for dynamically storing a portion of the film and forsensing deviations in the film length between the supply reel and theprojector to provide a control indication of either a film length excessor deficiency; second film control means located between the motionpicture projector and the film takeup reel for dynamically storing aportion of the film and for sensing deviations in the film lengthbetween the projector and the takeup reel to provide a controlindication of either a film length excess or deficiency; first means forselectively temporarily adjusting the operation of the first or secondfilm drive means responsive to said first control indications; andsecond means for selectively temporarily adjusting the operation of thefirst or second film drive means responsive to said second controlindication.
 5. Apparatus according to claim 4 wherein each of the firstand second control means include a biasable film looping mechanism.